Weft thread inserting mechanism for looms

ABSTRACT

This invention relates to a weft thread inserting device for a shuttleless loom comprising a pair of gripper rods having gripper heads mounted on the ends thereof, the gripper rods being mounted for reciprocating movement and being adapted to extend into the shed whereby a weft thread is transferred from one gripper head to the other, and clamping means on the gripper heads for the weft thread adapted to be positively actuated from the exterior of the shed.

United States Patent Kokkinis [451 May 30, 1972 s41 WEFT THREADINSERTING 3,390,707 7/1968 Scherillo ..139/122 MECHANISM FORLOOMS3,438,402 4/1969 Kokkinis 139/127 [72] Inventor: Nikolaus Kokkinls,Eriskirch, Gen'nany FOREIGN PATENTS QR APPLICATIONS 1 1 AssisneerLindauer Dornler Gesellschaft 190,266 12/ 1922 Great Britain ..139/127 RLindau/Bodensee, Germany 22 Filed: Jan. 19 1970 Primary Examiner-HenryS. Jaudon Attorney-James E. Bryan [21] App1.No.: 3,902 g I v [57] 1ABSTRACT [52] "139/!27 39,122 N This invention relates to a weft threadinserting device for a r [51] Int. Cl. "D0311 47/18 shuttleless loomcomprising a i of gripper rods having 0 r heads mounted on he ends h theg ipp rods being mounted for reciprocating movement and being [56]Rderences Cited adapted to extend into the shed whereby a weft thread istrans- UNITED STATES PATENTS ferred from one gripper head to the other,and clamping means on the gripper heads for the weft thread adapted tobe 3,6] Ravella N positively actuated from the exterior ofthe shed.3,384,126 5/1968 Golobort ..139/123 3,386,477 6/1968 Durand 139/123 10Claims, 13 Drawing Figures Patented May 30, 1972 3,665,975

9 Sheets-Sheet 1 INVENTOR NIKOLAUS KOKKINIS m Zw ATTORNEY 9 Sheets-Sheet2 EN I'INTOR NIKQLAUS KOKKINIS nmN Patented May 30, 1972 BY (}M @M nmmmPatented May 30, 1972 3,665,975

9 Sheets-Sheet 5 INVENTOR NIKOLAUS KOKKINIS ATTORN EV Patented May 30,1972 3,665,975

9 Sheets-Sheet 4 F 6 I mvmmn NIK'OLAU'S KOKKINIS av fm ATTORNEY PatentedMay 30, 1972 9 Sheets-Sheet 5 v wt 1 mv ENTOR NI KQLAUS KOKKINI 8ATTORNEY Patented May 30, 1972 9 Sheets-Sheet 6 BY M; fi

INVEN'IUR N'IKOLAUS KOKKINIS ATTORNEY INVENTOR NIKOLAUS KOKKINIS BY 2MATTOR N IEY Patented May 30, 1972 9 Sheets-Sheet 7 Patented May 30, 19729 Sheets-Sheet 8 FIG. 11a

ATTORNEY Patented May 30, 1972 3,665,975

9 Sheets-Sheet 9 INVEN'IOR NIKOLAUS KOKKINIS ATTORNEY WEFT THREADINSERTING MECHANISM FOR LOOMS The present invention relates to a weftthread inserting device or mechanism for shuttleless looms comprising apair of gripper rods which are moved in reciprocating fashion and engagein the shed at the same distance.

In a weft thread inserting mechanism of this type, one gripper rod ismounted on each side of the loom and is inserted into the shed from theside and retracted again. Mounted at the front ends of the gripper rodsare gripper heads which seize the weft thread to be inserted into theshed and guide it during the inserting operation or procedure. At thattime the weft thread is drawn off of a large supply spool mountedoutside of the shed.

Already known in the art are looms which place a weft thread that hasbeen drawn off of a supply spool onto the thread holder of the gripperhead in looped form, advance the weft thread to the center of the shedand there transfer it to the counter gripper, which latter will thenstretch out the weft thread loop to the end of the shed. This weavingmethod incorporating the double insertion of weft thread has, however,the specific disadvantage that the thread which is brought up has twicethe speed as compared to the gripper rod and that, as a result, it isstressed to an unnecessarily large extent at the thread reversing pointof the gripper head. This may easily lead to the weft thread being tornofi'. In accordance with a different prior method, the weft thread is nolonger inserted in a complete loop over the entire width of the shed,but instead is introduced in looped form only up to approximately thecenter of the shed. Thereafter, the loop on the inlet side of the shedis opened and, after the thread transfer, the single now free loop endis completely drawn through the second half of the shed. The thread isthereby extended or stretched until ultimately the free end of thethread will project or hang over at the edge of the fabric. It is truethat according to this method of inserting the weft thread only a singlethread need be introduced, but this method does involve the samedisadvantages and drawbacks which have been outlined hereinabove withrespect to the insertion of a complete loop.

Also known are looms which avoid the disadvantage of the loop insertionby placing the weft threads individually into the shed. According tothis method, a weft thread portion is brought to a clamping or grippingdevice, for example leaftype springs, being secured to the gripper head.This thread is advanced up to the center of the shed and thentransferred to the counter gripper. The transfer of the weft thread fromthe transmitting means to the receiving means takes place automaticallyby virtue of a specific construction of the thread holder at the gripperhead. For purposes of transferring the 'thread in the shed center,clamping hooks or clasps, for example,are used. The gripper whichreceives the clamped-in weft thread must, in tum,so hold or retain theweft thread after receiving in that, during the return movement of thegrippers, the clamping effect and, respectively, the friction of theweft thread at the transferring gripper, i.e., at the transmittingmeans, is effectively overcome and so that the weft thread is drawn outof the clamping device of the transmitting means. This importantrequirement, however, is not satisfactorily met during theabove-described automatic thread transfer with clamping springs. As aresult thereof, weaving flaws recur time and again. Whether the reasonbe that the weft thread is not taken over or received at all in thecenter of the shed, or whether it is only incompletely drawn through theshed and lost by the receiving means too early in any event, the weftthread ends at the fabric edge become unevenly long.

A further significant disadvantage of such clamping springs resides inthat, during the thread transfer, as mentioned, the weft thread is drawnoff of the clamping device of the transmitting means under tension. Thiswill result in an abrasion or wear and tear on the weft thread which notonly has the effect of damaging the weft thread but in which case thewom'olf particles become unpleasantly noticeable by soiling the thespring clips. Due to the soiling, the clamping effect is considerablyreduced, and under certain circumstances to such a degree that theentire clamping device breaks down. Additionally, these spring clampsfurther do not operate faultlessly at different thicknesses of the weftthread. Accordingly, it is not possible to process with this prior artmethod combinations of the weft threads of alternately coarse and finethreads with certainty.

It is therefore sought that this drawback be obviated by means of longerindividual weft threads andby subsequently cutting off the thread endsbeing uniformly too long. This, however, increases the waste of weitmaterial very considerably.

The present invention is based on the concept of constructing a weftthread inserting mechanism for shuttleless looms which are equipped withstationary supply spools for the weft thread and with a pair of gripperrods being moved in reciprocating fashion and engaging in the shed fromboth sides to approximately the same distance, wherein in the advancedor extended position of the gripper rods, for example in the center ofthe shed the weft thread is transferred or transmitted asindividualthread from the gripper head of one gripper rod to the gripperhead of the other gripper rod. In the present invention, the gripperheads are provided with clamping levers for the weft thread, whichlevers for the purpose of seizing and, respectively, releasing the weftthread are adapted to be positively actuated from the outside by meansof operating levers coupled to the main drive of the loom.

' In order to allow for a gentle opening and closing of the clampinglevers at the gripper rod heads, it is further proposed, according toanother embodiment of the present invention, that the clamping levers beconstructed in the shape of tongs and that a lever which is mountedoppositely with respect to the clamping part be equipped with a contactor bearing surface and, respectively, a running-up surface for theoperating levers. The clamping part may be provided, for example, with aprismatic clamping surface and come to be positioned within acorresponding prismatic bed as a counterpart or seat.

Asa result of this measure of the forced control of the weft threadtransfer it is now possible to accurately adjust or set the length ofthe weft thread so that, despite a rapid thread transfer, only a veryshort piece will remain as waste. Moreover, with this weaving method, aloop formation of the weft thread may be dispensed with entirely. Byreason of this construction of the clamping mechanism, it is effectivelyassured also that very short thread portions are faultlessly held at thegripper head. It is further apparent from the present invention thatthreads having different thicknesses may be equally employed. Anypossibly arising soiling within the clamping mechanism or device hassubstantially no influence upon the thread transfer and the weavingoperation as such.

The present invention will be further explained hereinafter by referenceto the accompanying drawings, wherein FIG. 1 is a simplified view of aloom;

FIG. 2 illustrates gripper heads with a clamping device or mechanismofthe present invention;

FIG. 3 is another illustration of the clamping mechanism at an enlargedscale;

FIG. 4 is a cross-sectional view through FIG. 3;

FIG. 5 is a view of the gripper heads and control therefor at anenlarged scale;

FIG. 6 is a top plan view of the gripper heads with internal releasinglevers;

FIG. 7 is a side view of the internal releasing lever control;

FIG. 8 is a side view of the external releasing lever control;

FIG. 9 is a sectional view of the loom according to FIG. 1 in a modifiedform thereof;

FIG. 10 is a difierent illustration of the construction according toFIG. 9 at an enlarged scale;

FIG. 1 1 illustrates schematically the operation of a loom according toFIG. 9,

FIG. 11a illustrates schematically the operation of a loom according toFIG. 1, and

FIG. 12 illustrates schematically the operation of the internalreleasing mechanism.

FIG. 1 is a schematic view of a loom. Reference numeral 1 designatestherein the frame of the machine. Mounted at the side thereof is thedrive motor 2 and all the movements are derived from his central drive.The drive shaft 10, on which the eccentric 11 is mounted, is driven bythe common gear 12 via the main drive shaft 13, and the gripper rods 17,18 are moved to and fro by means of the gripper rod gear 19. The gripperrod 17 is provided at the front end or end face thereof with the gripperhead 21 and the gripper rod 18 carried the gripper head 20. The twogripper rods with the gripper heads thereof have been shown in fulllines in the retracted position thereof when they are outside of theshed and in phantom in the extended position thereof approximately inthe center of the shed. The supply spool container 3 receives the weftthread supply spools 4. Positioned in the center of the machine is thecomb or reed 5 which is driven by the arms 6 of the reed shaft 7 andoscillated back and forth. Secured to this reed shaft 7 are also thedrive elements for the control of the gripper heads, such as the rollerlever 8 and the supporting arm 9, respectively.

The clamping devices or means at the gripper heads 20 and 21 which havenot been further illustrated herein are controlled in the center of theshed by means of the control mechanism and outside of the shed by meansof a corresponding releasing mechanism 16. The drive elements for thecontrol mechanism 15 are positioned on the reed shaft 7, as has alreadybeen mentioned hereinabove, and include the roller lever 8 and thesupporting arm 9. The drive thereof is effected by means of theeccentric disc 11, as will be more fully described hereinafter. Thereleasing mechanism 16 may be driven in a similar manner. In this caseit has been assumed that it is actuated by a shaft-sliding gear 14.

In the case of the loom which has been shown here as one embodiment, ithas been assumed that the weft thread is inserted at all times only fromthe left side as an individual thread. Accordingly, the left gripperhead 21 may be designated as transmitting means and the right gripperhead 20 may be designated as receiving means." The construction of thegripper heads has been shown in further detail in FIGS. 2 to 5. Duringthe weaving operation, the weft thread is offered to the left gripperhead, the transmitting means 21. For this purpose, the releasingmechanism 16 on the left side of the machine will be actuated andcontrols the clamping device at the transmitting means 21. The clampingdevice is opened for a short period of time and then closed again afterit has seized the weft thread which had been offered thereto. Once theweft thread has been conveyed by the transmitting means 21 up toapproximately the center of the shed, the control mechanism 15 willactuate the clamping devices of the transmitting means 21 and thereceiving means 20, and the weft thread will be transferred from thetransmitting to the receiving means. During the return of the gripperrods, the receiving means 20 will pull the weft thread completelythrough the shed. When the receiving means 20 has arrived outside of theshed, the clamping device at the receiving means 20 will be opened onthe right hand side of the machine by the releasing mechanism 16, andthe weft thread end is released.

It is apparent from FIGS. 2 and 3 how the gripper heads 20 and 21together with the clamping devices or means thereof are constructed. Theclamping devices consist of the doublearmed clamping levers 22 and 23,respectively, which are adapted to be pivoted in each case about thebearing 24 in a scissor-like manner. The arm of these clamping leversfacing away from the gripper tip is provided with a contact or bearingsurface and, respectively, a running-up surface 22a and 23a,respectively. A control lever will come to rest against this running-upsurface, as will be described in further detail hereinbelow, and pivotsthe arms downwardly, and hence the arm pointing toward the gripper tippivots the clamping portion 22b and 23b respectively of the clampinglevers upwardly. As a result thereof the clamping device will be openedat the two gripper heads 20 and 21, respectively. The position of theclamping parts 22b and 23b shown in phantom illustrates the positionthereof in the opened condition. In this position, the

weft thread is either inserted or taken out of the clamping device. Itis also apparent from this showing how the clamping spring 25 ispositioned and engages at the projection 26 in order to retain theclamping levers 22 and 23 in the closed position thereof due to springpressure. This spring 25 is constructed as a simple leaf-type spring andhas the effect that, during the insertion of a thicker weft thread, astronger pressure is correspondingly exerted upon the clamping point.This becomes significant in view of the fact that a thicker thread has aconsiderably greater mass and might therefore be lost under certaincircumstances during the rapid drawing of the weft thread through theshed if the same pressure for all thread thicknesses were exerted uponthe clamping device.

FIG. 3 is a view at an enlarged scale of the clamping device at thegripper head 21. Also distinctly apparent from this figure is theconstruction of the thread fork 28 at the gripper head 21. Since theleft gripper head 21, i.e., the transmitting means, is involved in thiscase, the thread fork 28 needs to be effective only in one direction.The positioning or support of the thread at the counter gripper head 20,i.e., the receiving means, with the thread hook 29 is shown in FIG. 2.

FIG. 4 is a cross-sectional view through FIG. 3 at the point indicatedby the arrow. The clamping device has the shape of a prismatic bed, asis clearly visible in the cross section. The clamping part or portion,for example 23b, has a prismatic configuration at the lower end 31thereof. A corresponding prismatic bed 27 in the gripper head 21 servesin this case as a counterpart and a support or seat. The prismatic bedis constructed as a plate and is secured to the gripper head 21. It alsocomprises the recess already mentioned above of the thread fork 28 atthe transmitting means 21 and, respectively, the thread hook 29 at thereceiving means 20. This particular type of construction of the clampingdevice is important because in this case the clamping length for thethread is considerably increased and the arrangement is practicallyequal to a looping or winding or a thread about a cylinder. It isthereby effectively possible that even a very short thread portion canbe perfectly retained. The clamping device at the counter gripper head,i.e., at the receiving means 20, is correspondingly constructed. Thisprovision and construction of the clamping devices assures the secureclamping and unimpeded release of the weft thread. The disadvantages anddrawbacks outlined hereinabove in connection with the prior art springclamps and the fiat tong-like clamping devices will thus no longerarise.

FIG. 5 shows a cut-out portion or section of FIG. 1, namely the controlmechanism 15 for the clamping devices at the gripper heads. Thismechanism includes the supporting arms 9 and the roller levers 8. Theconstruction and operation of the control mechanism will be explained infurther detail hereunder in connection with FIGS. 5 and 6.

FIG. 6 is a side view of the control mechanism 15. The supporting arms 9are clamped onto the comb or reed shaft 7 and concomitantly execute orcarry out the pendulum or oscillating movement of the reed. They areprovided at the ends thereof with a connecting rod 32 which is rotatablymounted in the supporting arms within the bearing 9a. Clamped onto theconnecting rod 32 are the control levers 34, or they are otherwisesecured thereto in a manner preventing relative rotation. During thecontrol operation for the weft thread transfer, these control levers 34will come to be positioned from above onto the supporting or contactsurface 22a and 23a, respectively, of the clamping levers 22 and 23,respectively.

As a further significant structural element, the control mechanism 15also includes the roller lever 8. It is rotatably mounted on the reedshaft 7 and carries a roller 8a which, under the action of a returnspring 36, will come to be placed against the constantly rotatingeccentric disc 11. By reason of the relative rotating movement of theroller lever 8 on the reed shaft 7, which arises during the rotation ofthe eccentric disc 11, the movement is transferred by way of anintermediate lever 8b to one of the control levers 34. The other controllever 34 is equally concomitantly moved by the simultaneously rotatingrod 32. It is understood that the intermediate lever 81; need not bedirectly connected to the control lever 34, as has been illustratedherein for the sake of simplicity, but may instead effect a rotatingmovement of the connecting rod 32 also in any other fashion, and hencean up-and-down movement of the control levers 34. It is readily apparentthat with the aid of the particular construction of the eccentric disc11 and the control mechanism 15, the desired control times or periodsfor opening and closing the clamping devices during the weft threadtransfer may be precisely maintained, or also may be modified asdesired, if such is necessary.

The mechanical coupling of the roller levers 8 with the reed shaft 7, onthe one hand, and the arrangement of the supporting arms 9 on the otherhand has the result that the control mechanism causes the control levers34 to be in the shed precisely at the predetermined period of time ormoment for purposes of actuating the clamping devices at the gripperheads. A stop member 40 with a setscrew 41 allows for a precisesettingof the rotary movements and, respectively, of the springdeflection or travel stroke for the roller lever 8.

FIG. 7 is a top plan view of the gripper heads and 21 with the internalcontrol mechanism 15. This figure shows the position of the gripperheads 20, 21 immediately prior to the transfer and acceptance orreception of the weft thread 30. The left gripper head 21 moreovercomprises an additional guide bar 33 which holds the weft thread at thereversing point in such a manner that an approximate loop will be formedand the counter gripper head 20 is adapted to accept and clamp in thethread 30. Only after the weft thread has been accepted by the receivingmeans 20 will the clamping device also open at the left gripper head,i.e., the transmitting means 21, and the thread 30 will be inserted orplaced in the shed due to the retraction of the right gripper rod 18.

This figure illustrates once more the arrangement of the supporting arms9 with the connecting rod 32 thereof and the control levers'34 beingsecurely clamped thereto. Also shown therein is the connection of theintermediate lever 8b to the control lever 34. The ends of the controllevers 34 will come to be placed from above onto the contact or bearingsurfaces and the running-up surfaces 22a and 23a, respectively, thusopening the clamping devices at the gripper heads 20 and 21,respectively. During this movement, the control levers 34 extend for abrief period of time and from the outside through the warp threads intothe shed.

The positive control of the clamping devices in the center of the shedproceeds in the following manner. In the present example, it has beenassumed that the control mechanism 15 is actuated only by means of asingle eccentric disc 11. For this reason the two control levers 34 aremoved simultaneously in the manner described above. The control of theclamping devices 22, 23 at the gripper heads 20, 21, however, takesplace asymmetrically so that the actual times for the opening andclosing of the clamping devices at the transmitting gripper head 21 andat the receiving gripper head 20 are chronologically shifted. When theopening or closing operation of one clamping means takes place while thecorresponding gripper head stands still, the control levers 34, whilebeing lowered,

. press down upon the contact or bearing surface 22a and 23a,

respectively, and thus open the clamping device, and respectively theywill close the latter when the control levers 34 are being lifted uponce again. The surfaces 22a and 230 may be effective, however, also asrunning-up surfaces when one gripper head slides under an alreadypreviously pressed-down control lever 34 and, respectively, is pulledout from under the control lever. The receiving means 20 leads thetransmitting means 21 with regard to time and achieves the most advancedor farthest extending position thereof within the shed ahead of thetransmitting means 21. The. clamping device 22 at the receiving means 20is opened by means of the control levers 34. Only thereafter will thetransmitting means 21 which carries the weft thread arrive at, or reach,the corresponding point in the shed and guide the weft thread into theclamping device 22 of the receiving means 20. Thereupon a brief parallelrun of both gripper heads takes place at which time the receiving means20 already runs backwards again and recloses the clamping device 22thereof. The transmitting means 21 will still continue in the forwardmovement thereof for a short path. During this parallel run or travel,the running surface 23a of the transmitting means 21, coming from theleft under the already pressed-down left control lever 34 is travelingso that also for the transmitting means the clamping device 23 is openedand the weft thread can be transferred. At the end of the paralleltraveling path, the two gripper heads become separated and also thetransmitting means begins it return movement. The control levers 34 arenow back in the position of rest thereof so that the clamping devicesboth at the receiving means 20 and at the transmitting means 21 areclosed. The weft thread has been transmitted from the transmitting means21 to the receiving means 20 and has been securely clamped in at thelatter. The shifting or operating times for the clamping devices and themovements of the gripper rods and, respectively, gripper heads areaccordingly displaced in phase to a certain extent. The phasedisplacement, i.e., the lead of the gripper rod 18 with the receivingmeans 20 as compared to the gripper rod 17 with the transmitting means21 takes place in a simple manner, for example by correspondinglydesigning the gripper rod gear 19 on both sides of the loom. The phasedisplacement for opening and closing the clamping devices is effected bya chronologically shifted or displaced arrival of the gripper heads, ashas been described above, under the simultaneously actuated controllevers 34.

FIG. 8 is a side view of the external releasing mechanism 16. As hasalready been described, the external releasing mechanism 16 is drivenseparately and mounted on both sides outside of the shed. The operationthereof is the same in principle as that of the internal controlmechanism 15. Here again, a sequence of movements is transferred via aneccentric 11a to a control lever 35 which acts upon the clamping lever22 and, respectively, 23 by virtue of spring tension. A bolt or tensionspring 36a presses the control lever 35 downwardly onto the running-upsurfaces 22a and 23a, respectively, of the clamping levers 22 and 23 assoon as the eccentric 11a renders it possible. The releasing mechanism16 on the left-hand side of the machine controls the opening of theclamping device 23 at the transmitting means 21 for the period of timeduring which the weft thread being drawn OR the supply spool is offeredto the transmitting gripper head 21 by means of a thread feeding device(not shown). In an analogous manner, the releasing mechanism 16 on theright-hand side of the machine will become operative only after the weftthread has been pulled completely through the shed by the gripper head20 and must be released. As far as the transfer'and acceptance of theweft thread approximately in the center of the shed are concerned, thereleasing mechanisms 16 have no significance. The releasing mechanisms16 outside of the shed may be constructed in the most diversifiedmanner. Essential is here again particularly the fact that the controllevers are moved by gear elements, for example eccentric discs, onlywhen the clamping devices at the gripper heads are intended to beactuated.

In the embodiment of FIGS. 1 and 5, respectively, a common eccentricdisc is provided for the control mechanism 15 mounted in the center ofthe shed. The time difference for the control of the two control levers34 is attained by an asymmetrical sequence of movements of the gripperrods and a thread transfer during a brief parallel travel of both grippeheads and gripper rods, respectively.

FIG. 9 shows a modified embodiment relative to this constructionaccording to which two separate control mechanisms 15 and 15a arepresent for the control of the clamping devices at the gripper heads 20and 21. Each control mechanism is controlled by a separate eccentricdisc 11 and 11b, respectively. The position of the two gripper heads 20and 21 as shown in phantom is merely intended as an approximateindication and does not correspond to the precise position at the timeof the thread transfer. The connecting rod 32 on which the two controllevers 34 were positioned in accordance with FIG. 1 is now divided intotwo parts both of which have been designated with reference numeral 32a.

The construction of FIG. 9 is again shown in FIG. 10 at a slightlyenlarged scale. Visible to the right is the control mechanism for thereceiving gripper head and at the left the control mechanism 15a for thetransmitting gripper head 21. Each control mechanism consists of twosupporting arms 9 and rotatably positioned at the end thereof within thebearing 9a is the connecting rod 32a. The control lever 34 is againsecurely clamped in on the connecting rod 32a. Shown between the twosupporting arms 9 is the roller lever 8 with the roller 8a. By means ofthe latter, the oscillating movement which has been initiated by theeccentric discs 11 and 11b, respectively, is further transferred via theintermediate lever 8b to the connecting rods 32a, as has been describedhereinabove. Illustrated next to the main drive shaft 10 to the left andright are side views of the two eccentric discs 11 and 11b, by way ofexample, in order to indicate that the eccentric discs may have a phasedisplacement and may be constructed in different fashion, if desired.The curved form of the eccentric disc as shown in the drawing is merelyintended to supply an impression of the possibly existing conditions; itdoes not correspond to the requirements as they arise during actualoperation. It is readily apparent that due to the choice of the curveshape of the eccentric and the rotation; or in other words, the phasedisplacement of the two eccentric discs with respect to each other, anydesired control time may be set and varied. The two gripper heads, thetransmitting means 21 and the receiving means 20, also are shown in thisfigure. By the position of these two gripper heads, the leadingcharacteristic of the receiving gripper head 20 is indicated.

The thread transfer takes place in the following manner. As soon as thereceiving gripper head 20 has arrived in the foremost position thereof,the control lever 34 is pressed upon the running-up surface 220 of theclamping device by means of the control mechanism 15, and the clampingdevice is thereby opened. The receiving means 20 is thus ready toreceive and accept the weft thread. Slightly later, the transmittingmeans 21 reaches its foremost position and guides the weft thread intothe opened clamping device of the receiving means 20 since in theforemost position thereof the two gripper heads will slightly overlapeach other. Thereupon the control mechanism 15 closes the clampingdevice 22 at the receiving means 20 once again and the weft thread issecurely clamped in. Only at this time will the opening of the clampingdevice 23 at the transmitting means 21 take place by means of thecontrol mechanism 15a. The receiving means 20 is then retracted andcarries along the clamped-in weft thread. Once the weft thread is pulledout of the transmitting means 21, also the clamping device 23 of thelatter is once again forcibly closed and the transmitting means 21 isretracted. The thread transfer thus takes place while the two gripperheads 20 and 21 are stationary in a manner such that at no time are thetwo clamping devices 22 and 23 opened simultaneously. The two controllevers are actuated at that time individually and separately. The threadis thereby firmly held at all times and can never be lost during thetransfer thereof. The thread transfer works perfectly also if differentthicknesses of weft threads, i.e., very thick and very thin weftthreads, are intended to be inserted alternately. Even in case the weftthreads project or overlap only by a short distance, these short endsare securely grasped and held by the clamping device. It is thereforepossible to accurately measure the length of the various weft threadsand thus attain a considerable reduction of the waste relative to theweft thread material.

Another advantage of this construction resides in the fact that the leadof the one gripper head as compared to the other may be shorter than inthe embodiment of FIG. 1, which means that the mutual gear displacementcan be considerably reduced. The unbalance of the entire machine thusbecomes smaller and the operation thereof smoother. Additionally, the

times needed for the transfer of the thread are considerably shortened,particularly because no parallel operation of the two gripper heads isrequired any longer. Due to the omission of the parallel travel, whichrepresents a type of relay race for the two grippers, there is achievedan increase of the usable weaving width about the length of the path ofthe parallel travel, provided the stroke of the gripper rods remains thesame.

FIG. 11 schematically illustrates, with reference to the embodiment ofFIGS. 9 and 10, the course of the thread transfer as described above in10 different positions. In the position one, the external releasingmechanism 16 at the transmitting means 21 opens the clamping device, andthe weft thread is inserted into the transmitting means 21 by means of athread feeding device. In positions two and three the weft thread isclamped into the transmitting means and the advance movement of thegripper heads has begun. Here the lead of the receiving means 20 hasbeen indicated. The thread transfer proper at the stationary position ofthe advanced gripper heads is illustrated in positions four to eight. Itis evident that at no time will the clamping devices of both gripperheads be open simultaneously. Position 9 shows the pulling-through ofthe weft thread during the return movement of the gripper heads. Inposition l0, both gripper heads have left the shed and the receivingmeans 20, forcibly controlled by the external releasing mechanism 16,releases the weft thread. Position 1 I already shows once more thebeginning of the new cycle.

FIG. 11 also illustrates that the left control lever 34 is actuatedindependently of the right control lever. At that time, the receivinggripper head has the positions four to seven, while the transmittinggripper head 21 has the positions five to eight, in the position of restthereof.

FIG. 11a schematically illustrates, with reference to the embodiment ofFIG. 1, the course of the thread transfer as described above in 10different positions. From this figure, it is evident that in thepositions five to seven, both grippers, i.e., the receiving means 20 andthe transmitting means 21, extend in a parallel manner for a portion ofthe travel thereof and transmit the thread during this parallel courseor path. In this case, the control levers 34 are so coupled to eachother that they execute their movements simultaneously. They are presseddown for the entire duration of the positions five to seven. The openingand closing of the clamping means is effected partially by depressingthe control levers onto the contact or bearing surface and partiallyalso by virtue of the fact that the grippers, with the running-upsurfaces thereof, are slid under the pressed-down control levers 34 andthen retracted.

The sequence of operations of the control levers is shown schematicallyin FIG. 12. Apparent therefrom is the position of the supporting arms 9,of the intermediate lever 8b and of the control lever 34 for differentperiods of the weaving operation. The showing of the various positionscorresponds approximately to positions one through 10 in FIG. 11. Alsoshown therein are the positions of the eccentric disc 11 and of theroller 8a as well as the positions of the reed 5 and of the gripper head20, corresponding to the various positions. It is apparent that thecontrol lever 34 is initially situated outside of the shed (positionsone through three). Only shortly before the gripper head 20 attains theadvanced position thereof in the center of the shed will the controllever 34 be introduced from the outside through the warp threads of thelower shed into the shed (position four). The guide member 20 is mountedon the gripper head and slides along the reed 5. As soon as the controllever 34 actuates the clamping means, the gripper head will be securelypressed with its guide member 20 against the reed 5. Vibrations duringthe transfer of the thread are thereby effectively supressed and theposition of the gripper head is fixed and centered. Guide members ofthis type are present both on the receiving gripper head 20 and on thetransmitting gripper head 21. For purposes of the thread transfer, thecontrol lever 34 presses the contact surface of the clamping devicedownwardly for a short period of time and is again lifted up thereafterinto the previous position (positions tive and six). After the gripperhead 20 has started its return movement, the control lever 34 is againpulled out of the shed (positions seven to 10). For the purpose offixing the wefi thread, the reed 5 and together therewith the supportingarms 9, the intermediate lever 8b and the control lever 34 are pivoted.At that time the roller 8a lifts off the eccentric disc 11. Thissequence of movements is valid generally for the two above-describedembodiments of the weft thread inserting device.

ln FIGS. 1 and 9, the thread feeding device between the supply spool 4and the gripper head 21, which is actually necessary, has not beenshown. In'order to render it possible that the weft thread and several,for example differently colored weft threads, be selectively offered orsupplied to the gripper head 21, a specific interstice is needed betweenthe edge of the fabric and the gripper in the retracted positionthereof, which interstice is not required on the counterside, i.e., onthe receiving side of the machine. As a result thereof, the center ofthe fabric sheet or width is positioned slightly offset in the directiontoward the other side of the loom as compared to the symmetrical strokeof the gripper rods 17 and 18 and the gripper heads 20 and 21. It ispossible in this manner that, despite the lead of the gripper head 20,both gripper heads 20 as well as 21 are retracted substantiallysimultaneously out of the shed. This constitutes a marked advantage.Without this particular measure it would be necessary to wait until thetrailing gripper head left the shed in order to close the latter andcast on the weft thread, which would, however, result in a loss of time.If, on the other hand, the closing of the shed were initiated before thetrailing gripper 21 had completely left the shed, damage to the warpthreads would be produced. All of these disadvantages are avoided bymeans of the aforementioned displacement of the entire width of fabric.

The release of the drawn-through weft thread by the receiving gripperhead 20 takes place advantageously by means of the releasing mechanism16 being mounted laterally with respect to the shed and at a time whenthe binding-off of the fabric edge clearly prevents any jumping back ofthe weft thread. In case of weft thread material which is not delicatein this respect, the release obviously can take place at an earliertime.

A further advantage of the construction proposed in FIG. 9 as comparedto FIG. 1 resides in that the transmitting gripper head 21 cannot bymistake automatically be opened. In case of flaws in the shed, forexample so-called nests, it is possible that the gripper rod is liftedduring the advance thereof so that in the raised position thereof therunning-up surface 23a of the clamping device erroneously strikes tooearly upon the control lever 34 and that therefore the weft thread willno longer be clamped in but is possibly lost. In other words, the threadslips out of the transmitting means before the thread transfer hasactually been effected approximately in the center of the shed.

Due to the positive control of the loom, it is now possible to shortenthe working cycles or strokes at the machine, whereby an increasedweaving velocity is achieved. In addition thereto, it is possible in asimple manner, with the aid of the special clamping device proposed bythe present invention to also alternately utilize weft threads havingdifferent thicknesses, i.e., irrespective of whether a single thread orweft thread combinations having different thicknesses are intended to beprocessed. Furthermore, any possible soiling of the clamping devicecannot prevent the weft thread from being securely held. Also, thecontrol lever affords the advantage of representing an additionalsafeguard of the gripper rods against breaking-out and of effectivelysuppressing any possibly arising vibrations. The entire weaving processmay be carried out at an increased speed by virtue of the automaticcontrol, i.e., higher weaving speeds are attainable. By reason of theperfect thread transfer between the two gripper heads and the securepositioning and holding of the thread until it is completely drawnthrough the shed, weft thread ends having a uniform length are obtainedat all times at the fabric edge. The projecting thread ends may a prioribe dimensioned short so that the waste relative to the weft threadmaterial is reduced to a minimum.

In connection with the present invention it is of particular advantagethat the wefl thread, during the transfer thereof, is not pulled out ofthe clamping device of the transmitting means under tension, but thatthe thread is transmitted or transferred without tension. Any damage tothe wefi thread or a troublesome abrasion are thereby effectivelyeliminated. The control levers for actuating the clamping devices areeither positioned laterally with respect to the shed, or extend into theshed, approximately to the center thereof, only for a brief period oftime. Accordingly, they do not adversely affect the remainder of theoperations.

It will be obvious to those skilled in the art that many modificationsmay be made within the scope of the present invention without departingfrom the spirit thereof, and the invention includes all suchmodifications.

What is claimed is 1. A weft thread inserting device for a shuttlelessloom in which successive sheds are formed comprising a pair of gripperrods having gripper heads mounted on the ends thereof with each gripperhead including a clamping means, the gripper rods being mounted forreciprocating movement into a shed, one of said clamping means beingadapted to clamp a weft thread at one side of the shed and draw it intothe shed center to be transferred from said one clamping means to theother and drawn through the other shed half, and each of said clampingmeans on the gripper heads being adapted to be positively actuated bypivotal means which penetrate the shed from he exterior thereof about atthe shed center.

2. A weft thread inserting device according to claim 1 in which theclamping means comprises clamping levers actuated by control meansincluding levers coupled to the main drive of the loom.

3. A weft thread inserting device according to claim 2 in which theclamping levers are tong-like double-armed levers and the lever armopposite to the clamping portion includes a bearing surface and arunning-up surface for the control levers.

4. A weft thread inserting device according to claim 2 including rollerlevers connecting the control levers with the reed shaft of the loom andcam means on the loom drive shaft for effecting the movement of thecontrol levers.

5. A weft thread inserting device according to claim 2 includingadditional control lever means mounted on each side of the loomlaterally outside of the shed for purposes of positive control ofreceiving the weft thread offered to one clamping means and,respectively, for the purpose of releasing the weft thread pulledthrough the shed by the other clamping means.

6. A weft thread inserting device according to claim 5 includingseparate control and releasing means with separate cam disc drive foreach of the control levers and additional control lever means positionedapproximately in the center of the shed and laterally outside of theshed, respectively.

7. A weft thread inserting device according to claim 2 including springmeans biasing the clamping portions into engagement.

8. A weft thread inserting device according to claim 2 including commoncam means coordinated to the control levers, the release of the weftthread by one clamping means and the seizing thereof by the otherclaiming means being effected by an asymmetrical advance of the gripperrods.

9. A weft thread inserting device according to claim 2 includingseparate control means each being separately and independentlycontrolled by separate cam means and being coordinated to the controllevers.

10. A weft thread inserting device according to claim 2 in which theclamping portions of the clamping means are prismatically shapedelements forming the upper portions of the clamping means, the upperportions in the closed position thereof engaging prismatic bedcounterparts rigidly mounted on the gripper heads.

1. A weft thread inserting device for a shuttleless loom in whichsuccessive sheds are formed comprising a pair of gripper rods havinggripper heads mounted on the ends thereof with each gripper headincluding a clamping means, the gripper rods being mounted forreciprocating movement into a shed, one of said clamping means beingadapted to clamp a weft thread at one side of the shed and draw it intothe shed center to be transferred from said one clamping means to theother and drawn through the other shed half, and each of said clampingmeans on the gripper heads being adapted to be positively actuated bypivotal means which penetrate the shed from he exterior thereof about atthe shed center.
 2. A weft thread inserting device according to claim 1in which the clamping means comprises clamping levers actuated bycontrol means including levers coupled to the main drive of the loom. 3.A weft thread inserting device according to claim 2 in which theclamping levers are tong-like double-armed levers and the lever armopposite to the clamping portion includes a bearing surface and arunning-up surface for the control levers.
 4. A weft thread insertingdevice according to claim 2 including roller levers connecting thecontrol levers with the reed shaft of the loom and cam means on the loomdrive shaft for effecting the movement of the control levers.
 5. A weftthread inserting device according to claim 2 including additionalcontrol lever means mounted on each side of the loom laterally outsideof the shed for purposes of positive control of receiving the weftthread offered to one clamping means and, respectively, for the purposeof releasing the weft thread pulled through the shed by the otherclamping means.
 6. A weft thread inserting device according to claim 5including separate control and releasing means with separate cam discdrive for each of the control levers and additional control lever meanspositioned approximately in the center of the shed and laterally outsideof the shed, respectively.
 7. A weft thread inserting device accordingto claim 2 including spring means biasing the clamping portions intoengagement.
 8. A weft thread inserting device according to claim 2including common cam means coordinated to the control levers, therelease of the weft thread by one clamping means and the seizing thereofby the other claiming means being effected by an asymmetrical advance ofthe gripper rods.
 9. A weft thread inserting device according to claim 2including separate control means each being separately and independEntlycontrolled by separate cam means and being coordinated to the controllevers.
 10. A weft thread inserting device according to claim 2 in whichthe clamping portions of the clamping means are prismatically shapedelements forming the upper portions of the clamping means, the upperportions in the closed position thereof engaging prismatic bedcounterparts rigidly mounted on the gripper heads.